Construction worker Joel Loza puts on his bandana after soaking it in water in an effort to keep cool Thursday. in Gilbert Ariz

LAS VEGAS — A high pressure system parking over the West for the weekend and into next week is expected to bring temperatures that are extreme even for a region used to baking during the summer.

Notoriously hot Death Valley’s forecast calls for 129 degrees, not far off the world-record high of 134 logged there July 10, 1913. The National Weather Service called for 118 in Phoenix, and 117 in Las Vegas on Sunday — a mark reached only twice in Sin City.

“It’s brutal out there,” said Leslie Carmine, spokeswoman for Catholic Charities, which runs a daytime shelter in Las Vegas to draw homeless people out of the heat and set them up with sunscreen and bottled water.

Meteorologists are calling for highs at or above 112 through Wednesday in Las Vegas, and there isn’t even relief when the sun goes down. Sunday night’s low is forecast to be 92 degrees — enough to make for a stuffy stroll down the Strip at whatever hour tourists leave the bar.

While the Southwest boasts the most alarming temperatures, the heat wave is driving up the mercury all over the West. Western Washington — better known for rainy coffee shop weather — should break the 90s early next week, according to the weather service.

Dry southern Utah is forecast to reach higher than 110 degrees, and northern Utah — which markets “the greatest snow on Earth” — is also expected to hit the triple digits.

The heat wave is “a huge one,” National Weather Service specialist Stuart Seto said. “We haven’t seen one like this for several years, probably the mid- to late 2000s.”

The system’s high pressure causes air to sink and warm, drawing down humidity.

“As the air warms, it can hold more moisture, and so what that does is take out the clouds,” Seto said.

While those in the West take to their swimming pools or hunker down indoors during the heat wave, the eastern half of the country is set for normal and below normal temperatures driven by lower pressure.

“There’s a balancing act in the atmospheric pressure,” said Chris Stachelski, a National Weather Service meteorologist based in Las Vegas. He noted that an unusual June heat wave that’s had Alaskans shedding their polar fleece in favor of bathing suits is part of a separate high-pressure system centered in the Yukon.

The hottest cities in the West are taking precautions to protect vulnerable residents during the sizzle. Police are pleading with drivers not to leave babies or pets in vehicles, and temporary cooling stations are popping up to shelter homeless people and seniors on fixed incomes who hesitate to use the air conditioning.

Officials said extra personnel have been added to the U.S. Border Patrol’s Search, Trauma, and Rescue unit as people illegally crossing the border from Mexico into Arizona could succumb to exhaustion and dehydration.

Several bodies of immigrants have been found in the last week in Arizona. Agents in the Tucson sector rescued more than 170 people from the desert during a 30-day stretch in May and June when temperatures were even lower than expected in the coming days.

At low-lying Lake Mead, which straddles the Arizona-Nevada border and is anticipating 120 degrees this weekend, rangers are positioned at trailheads to discourage hikers.

Earlier in June, a group of Boy Scouts hiking in the Colorado River canyon fell victim to soaring heat. Four teenagers and an adult had to be rescued, while a 69-year-old Scout leader died.